Rufus Sewell is getting a little twitchy. And his discomfort is contagious. The way he drags his feet the mere 50 yards from his publicist's Soho office to the Groucho Club could make a sensitive journalist feel paranoid. But as he hovers on the threshold, Rufus reveals why he's reluctant to enter London media-land's favourite watering hole.

"It's a bit embarrassing, actually," he apologises. "It's not that I don't want to do the interview, it's just that I haven't paid my bar bill." Nobody at the Groucho, however, seems the least bit troubled by the matter of Rufus Sewell's unpaid tab. But then the 26-year-old actor has the sort of unutterable charm which lets him get away, if not with murder, then certainly with the odd favour here and there. "I've always been a terrible flirt," he smirks.

British audiences have already been able to savour his bohemian good looks for themselves in the likes of Don Boyd's "Twenty-One", Michael Winner's "Dirty Weekend" and the BBC's "Middlemarch"; as we cross the Groucho to our table, every female head swings to catch a glimpse of the man the tabloids have yawnsomely dubbed "Sexy Sewell". Not everybody wants Sewell all of the time, however: the actor had to battle doubts about his suitability to land the role of Irish bus driver Bobbie in his latest film, Suri Krishnama's "A Man Of No Importance", in which he stars opposite an illustrious cast including Albert Finney, Brenda Fricker, Michael Gambon and Tara Fitzgerald.

"There were people on the Irish production side who reacted very negatively to the idea of having 'that twat from Middlemarch - the wet-lipped, poncy English bloke'," admits Sewell. "Hearing that made me really determined. Getting the part became more important to me than anything else in the world because someone thought I couldn't do it."

Despite the director's insistence that Rufus was the only man for the job, the part continued to elude him. "it was me and Suri versus them," says Sewell, with a triumphant grin. "It looked like we were losing, but in the end I did a screen test and they didn't even realise it was me - which says it all, really."

The film revisits the storv of Oscar Wilde through the experiences of Alfie Byme (Albert Finney), a bus conductor in '60s Dublin who recites Wilde to his passengers, and realises that, like the great playwright, he may be gay. For Sewell, who plays the object of Alfie's desire, the prospect of working opposite such an esteemed thespian as Finney was daunting. "I'd made the mistake of watching Albert Finney in Tom Jones before I started filming," says Sewell, "but my nerves went away quickly because working with him is so easy. You'd sit there having a little chat, they'd call action and then cut and you'd realise that in between you'd done the scene."

"On the first day," he continues, "I asked him some nerdy question about whether he thought it [A Man Of No Importance] was any good and he said, 'Oh fuck it, it's only a film.' It was the best thing to say to me because I was jumping around like a nervous, excited little dog, trying to be cool."

Producing a Dublin accent on a par with the virtually all-Irish cast gave Sewell the excuse to sample gallons of Ireland's most famous export. "Oh, getting the accent right was a real challenge, requiring endless research in Dublin's pubs," he quips. "I spent a lot of time going from one pub to another in taxis. I'd take my tape recorder and ask the driver to tell me about the perfect pint of Guinness. I made a collection of the Guinness tapes which I'd take home and spend hours repeating each phrase."

He may joke about his research methods, but Sewell is a meticulous professional who will go to any lengths to get the kind of realistic performance he needs to feel satisfied. On the set of "Carrington", Christopher Hampton's forthcoming directorial debut on the life of Bloomsbury painter Dora Carrington (played by Emma Thompson), Sewell went to extreme measures to work himself up into a suitably turbulent state of mind to play Carrington's thwarted lover, the painter Mark Gertler.

"It was embarrassing being caught smashing my head against a wall," confesses Sewell, whose self-abuse was spotted by Hampton himself during a break in filming. "I just did it because I was getting pissed off with the way I was doing a scene. I wanted my head to hurt so it would stop me from concentrating on anything else. We did a few takes and all I could think of was, 'Fuck, my head hurts."'

Sewell grew up between Wales, Soho and Twickenham, a self-confessed delinquent who hated school, regularly shoplifted and could only raise any interest in his drumming. "At 13, 1 was the youngest drummer in town playing the crap Twickenham pub circuit," he recalls. "By 14 I'd peaked and was as good at drumming as I'd ever be. Acting was the only thing I came across which I wasn't as good at as I could be."

"Thank god I became an actor," he continues, "or I would've ended up in fucked-up trouble. I was always stealing sweets and top ten records from Woolworths. I never got caught until years later when I was out of practice and literally starving at drama school. I got caught nicking peppered mackerel and houmous. It wasn't like in the Beano comic - 'Oh, you're obviously hungry, here's some nosh.' It was, 'You're obviously hungry, here's a police cell, you little fucker."'

Acting may have saved him from ending up in prison, but it was prison where he ended up when he took his first acting job behind bars. "I shaved my head and joined a theatre company touring prisons," he says. "We went to about 30, including Strangeways. It was a brilliant experience. It made you hate audiences from posh theatres. At least with a prison audience if they didn't understand what you were doing they'd say you were crap. It was slightly horrific, but refreshing. It got a bit scary sometimes in the women's prisons," he continues. "They got a bit frisky. The women knew they could scare us, so they had fun toying with us. Some of the women were very nice, actually - and, yes, there were times I was tempted."

But those days are long past and Sewell hasn't, of course, been inside a cell for some time, preferring to hone his craft in front of a wider audience. Now much in demand in TV, theatre and film, Sewell is being hailed as one of Britain's most exciting prospects on the international scene. Today, he's barely 24 hours off the plane from New York where he was the only member of the cast in the Broadway production of Brian Friel's "Translations" to receive rave reviews from the notoriously merciless Manhattan theatre critics - though "there wasn't a great deal of pleasure in being the only one who didn't get shat on," admits Sewell. "I couldn't really go round grinning from ear to ear."

After the play closed (prematurely), Sewell hung out in the Big Apple in the apartment he shared with his "Man Of No Importance" co-star Tara Fitzgerald, who was in New York for the run of "Hamlet" with Ralph Fiennes. "There's no romance with Tara," says Sewell quickly, "she's just an old friend who's been staying in the spare room. I've known her for years because she was best friends with my ex-girlfriend."

The magic prefix "ex" hangs in the close afternoon air of the Groucho as female ears at neighbouring tables eagerly prick up. "Yes, I'm free and single," confirms Sewell. "I split up with someone in the first few months of being in America. I've just come away from a few situations in New York and I'm not eager to get involved in something straight away. I've just been enjoying tarting around."

Although Sewell likes a bit of fun, his passion for a walk on the wild side conversely keeps the actor at arm's length from the temptations of LA. "It's the sort of place where you go to 15-year-olds' parties, think you're having a great time, but wake up with the faint smell of sick and loads of really embarrassing images floating through your mind," he explains. "If I wasn't susceptible it wouldn't bother me, but it's the secret fear that I could easily turn into an absolute shit-faced arsehole which keeps me away from LA."

And on that note, the charming and eminently eligible Rufus Sewell turns on his heel and makes an exit. A surprising character for sure. But when the waitress presents the bill for our afternoon's aperitifs, there's another surprise in store. "There's Mr. Sewell's outstanding bill to be taken care of," she declares. What can you say? Sorry, Rufus, But some things never change.